Pyridine iodinated butyl rubber



Oct. 9, 1962 1.. s. MINCKLER, JR.. ETAL 3,957,334

PYRIDINE IODINATED BUTYL RUBBER 3 Sheets-Sheet 1 Filed Dec. 23, 1959FIGURE-l 2 8 M m-250m ZO mWmSSZ M259 2 l INTRINSIC VISCOSITY IODINENUMBER REACTION TEMPERATURE, C.

Leon Sherwood Minckler,dr. Delmer L. Coflle lnvenrors Clifford W.Muessig By PutenI Attorney Oct. 9, 1962 s. MINCKLER, JR, ETAL 3,057,834

PYRIDINE IODINATED BUTYL RUBBER Filed Dec. 23, 1959 3 Sheets-Sheet 3FIGURE?) Relation Of Iodine Concentration To Cure Rofe For Pyridine-Iodinorion Of Butyl F (ATI2OC. IN CHLORQBENZENE) 6 Q. i 9 800 '2 (9 5LLI g 400 D O O 2 O I l I l I l 0 IO 20 3O 4O 5O 6O CURE TIME (MINUTESAT 307 F.)

Leon Sherwood Minckler, Jr. Dolmer L..Cofile Inventors Cllfford W.Muessig Patent Attorney United States Patent Ofifice 3,057,834 PatentedOct. 9, 1962 This invention relates to a method of modifying butylrubber. More particularly it relates to a method of increasing theiodine number of butyl rubber by treating it at carefully controlledconditions with elemental iodine and a pyrridine type amine.

This application is a continuation-in-part of Serial No. 781,449, filedDecember 19, 1 958.

Butyl rubber, a term well known in the rubber art, e.g. chapter 24 inSynthetic Rubber, edited by G. Whit-v by, is a rubbery copolymercomprising a major proportion of an isoolefin having 4 to 8 carbon atomsand a minor proportion of a multiolefin having 4 to 14, preferably 4 to8 carbon atoms. The most commonly employed isoolefin is isobutylene,although other isoolefins such as 3-methylbutene-1 and 4-methylpentene-1may be used. Suitable multiolefins, which are generally conjugateddiolefins, include isoprene, butadiene-1,3, dimethylbutadiene-1,3,piperylene and the like. Most of the copolymers contain about 90 to 99.5wt. percent isoolefin and 0.5 to 10 wt. percent diolefin, which in mostinstances is isoprene. The polymerization is generally carried out at alow temperature, e.g. between -50 to 165 C., in the presence of aFriedel-Crafts catalyst, such as aluminum trichloride, dissolved in alower alkyl halide such as methyl chloride, ethyl ch'oride, etc. Theirpreparation is fully described in US. Patent 2,356,128. Butyl rubbershave a viscosity average molecular weight between about 200,000 and1,500,- 000 or more and a Wijs iodine number between about 1 and 50.

It is desirable to increase the iodine number of butyl rubber so as toeffect more rapid rates of cure as well as to obtain other improvedproperties. One of the suggested means has been to halogenate thepolymer. Previous attempts to iodinate butyl rubber have not beensuccessful, giving only gelation, degradation, or no reaction at all. Onthe other hand treatment with elemental chlorine and bromine results inthe retention in the polymers of a considerable amount of these halogenswhich can be undesirable.

It has now been found that butyl rubber can be successfully modified andthe iodine number increased by treating it at carefully controlledconditions with elemental iodine and a pyridine-type amine at elevatedtemperatures in the presence of a high boiling polar solvent.

The products obtained exhibit several interesting and unexpectedproperties. Surprisingly enough, no significant amount of iodine remainsin the modified polymer. However, the iodine number is increasedmarkedly and by a controlled amount depending on the reactionconditions. In addition, the Mooney viscosity of the polymer isincreased sharply as a function of the iodine number with nocorresponding change in intrinsic viscosity.

The vulcanizate properties of the pyridine-iodinated polymer are alsoimproved. These improvements include significant increases in cure rateand dynamic properties.

The elemental iodine is utilized in an amount of from 1 to 25 wt.percent based on the polymer, Since it does not remain in the product itcan be recovered.

The pyridine-type amine compounds which are. within the purview of thepresent invention are those hetero- 2 cyclic compounds included in thetertiary amine class which have the following general formulae:

and

in which y is selected from the group consisting of R, OR, and OH; Rbeing selected from the group consisting of C to C alkyl, cycloalkyl,aryl, aralkyl and alkaryl; n being an integer of between about 0 and 3.In other words, compounds having a pyridine or quinoline nucleus areemployed. The pyridine-type compound is utilized in an amount of from 1to 100 wt. percent based on the copolymer.

The temperature of the reaction has been found to be important. Thus atemperature in the range of about to 150 C. has been found suitablesince at temperatures below this the reaction is too slow to bepractical.

The time of reaction also has to be controlled and is preferably in therange of about A to 2 hours and the time may be shortened by heating tostill higher temperatures, under pressure if necessary.

The solvent has also been found to be important. High boiling polarsolvents or low boiling polar solvents under pressure can be usedsuccessfully while hydrocarbons such as n-heptane, isooctane, decalinare much less satisfactory. The polar solvents that can be employedinclude aryl halides, such as chlorobenzene, ethers, e.g.tetrahydrofuran and di-n-butyl ether. Especially effective and desirableare monochlorobenzene, nitromethane, nitrobenzene and carbon disulfide.

As a result of the reaction of this invention the iodine number issubstantially increased. Iodine number of can be obtained by selectionof reaction temperature, time, solvent, etc. However, optimumutilization of this method occurs when the iodine number is aboutdoubled;

The product obtained is substantially free of iodine, i.e. contains nomore than 0.25% iodine (or 0.01 mole per 100 g. polymer) or about 2% ofthe theoretical amount which could go in by other halogenations.

The products can be recovered by precipitation with about an equalvolume of acetone followed by acetone wash in a blender. It can then bere-dissolved in a hydrocarbon such as heptane, re-precipitated andre-washed with acetone again. Drying is conveniently accomplished atpressures below 200 mm. of mercury.

This invention and its advantages will be better understood by referenceto the following examples of the treatment of an isoprene-isobutylenebutyl rubber having a mole percent unsaturation of 1.5 to 2.0 and aMooney 212 F. at 8 min. of 71+.

Details of the treatments and results are shown in Tables I and II. Theyare further discussed in the examples.

3 TABLE I Pyridine-Iodination f Butyl EXAMPLE 1 FIGURE I showscontrolled iodine reaction in the Diluent P1101 P1101 P1101 absence ofpyrldlne. Thls FIGURE demonstrates: Reagents, pyridine, ml- 10 10 10 10(1) The absence of pyrldlne results 1n no lncrease 1n Reaetants, iodine,gm 1. 3. 2 6. 4 12. 7 Conditions, C./h0urs.. 120 120 05 120 05 120 0. 5lodme numberrroduonpe r cent i ld- 02 99 90 99 (2) The polymer normallybreaks down at the term Iodine num er, cg. g. 12. 12.5 16.0 21.5lwlitrmsic ,t 2 5F 1 g L 2% L 44 perature utlllzed in this lnventlon. 1ooney viscosi y, 0 74 Percent ehlorine-- 0. 1 0. 1 0. 1 0. 1 EXAMPLE 2Percent iodine 0.1 0.1 0. 1 0.1 The butyl rubber sample was treated wlthpyrldlne and Percent iodine for 150 minutes. The iodine number increasedin C d 5, gg jg a linear manner although polymer vulcanizate propertiesure 8 7 .2

Modulus past/300% 185 170 290 515 do not 1mprove much after the 1od1nenumber has doubled. Tensile, p.s.l 1,500 1,170 2,045 2,400 The iodlnenumber also goes up will increasing iodine CurgOfil; plencent 930 875860 770 concentration- Iodnlus, p.s.i./300% 2 go 2 305 335 2 545 EXAMPLE3 ens'le, .s.i 0 ,47' 2, "10 ,525 g fi percent 660 2 675 FIGURE II showshow the Mooney vlscoslty increases Cured at with io i umber. ake r dModulus, p.s.i./300% 970 990 1,045 1,005 d Tjhls m for a P oduct adaptegensil nsi 2, 370 1,000 2, 470 2,430 for 011 eXte1151011 and 1113111021111118- longation, percent 615 565 595 615 Cured 51307 3.: 20EXAMPLE 4 Modulus, p 300% 1, 155 1,100 The modified butyl rubber wascompounded on a cold ensile,p.s.i 0 1, 5 1,940 1, Elongation, percent500 520 500 485 mlll uslng the f0rmulat1on shown below. Thls particularCured 513070}: formulatlon wlth a non-remforcmg black and high sulfur{23g g h g2 content was used to bring out differences in cure rate and GdEllollllggtion, p'erce4n5t; 470 445 405 375 25 vulcanizate propertiesresulting from variations in the 00 1C BXOHlE er Dynamic drift, percent8.6 8.0 6.5 4.8 unsaturatlon of these polymers Lina] dynamic ctomp,peg-centv 1.1% 10.2 9. g 8 Parts ompression se percen 12. 11. 9. .4Maximum temp. rise, C- 19 18 18 17 Polymer 50 max. temp, nun--- 13 13 1413 Pelletex (SRF) (furnace black pellets) 50 sfifi fifjjjjjj j 50 5 8 5330 y ap y ne 0.2 Mmfiey scorch (30/260F 2 Zinc stearate 1.0 M15 n I 19 31E9! 53 Zinc OXid Ms 21' 21' 1s 10 Sulfu 2 0 v1 r 1 1 r 74 73 89 00Tuads 1'0 TABLE II Pyridine-Iodination of Bulyl Butyl 203 Diluent P1101PhCl PhCl PhCl 11-0, 11-C1 P1101 Reagents, pyridine, m1- 10 10 10 16 1010 10 0 Reactants, iodine, grn 12.7 12.7 12.7 20 0.3 12.7 12.7 12.7 12.7Conditions, C./hours 80/1.0 30/00 /25 120/05 80/05 80/05 100/1.0 120/0550/1.o Product, percent yield. 9s 90 09 99 93 90 92 Iodine number, cg.Ilg 15.4 13.5 48.4 44.0 11.0 11.0 17.4 21.8 11.5 Intrinsic viscosity 1.54 1. 52 1. 39 1. 3s 1. 53 1. 55 1. 52 1.44 1. 4s Mooney viscosity,3/260 50 01 80 83 50 53 55 52 53 Percent chlorine 0.1 0.1 0.26 Percentiodine-.- 0.11 02 0. 43 9. 1 0. 1 0. 1 0. 1 0. 1 0. 1 Percent nitrogen0.01 0.01 0.02 0.02 0.01 0.01 0.15 0.31

COMPOUND Cured 5 at 307 F.:

Modulus, si/300%. 240 200 400 515 300 340 105 195 210 Tensile, p.s.i.--1, 070 2, 050 1,050 2,515 1,320 1, 305 1,905 2,200 985 1,500 1,940Elongation, percent..- 875 330 000 740 1, 100 1, 035 825 045 1, 215 955875 Cured 15 at 307 F.:

Modulus, .s.i./300% 025 000 320 850 040 055 010 035 005 715 500 Tensile,p.s.i 2,525 2,490 2,115 2,705 2,215 2, 375 2,510 2,440 2, 535 2,4952,575 Elongation, percent- 700 715 555 005 000 075 735 725 755 735 725Cured 25 at- 307" F.:

Modulus, si/300%. 705 340 1, 000 1, 575 595 315 795 925 345 005 Tensile,p.s. 2,450 2,470 1,135 2,570 2,425 2,425 2, 335 2,305 2,255 2,530 2,025Elongation, percent- G75 045 355 590 630 630 660 065 640 685 600 Cured45 at 307 F.:

Modulus, p s i./300% 945 1,000 1,275 1,020 975 1,000 1,020 1,010 1,1401,035 1,000 040 Tensile, p. 2,275 1,175 2,200 1,900 1,550 2,135 2,220 2,240 2,170 2,115 Elongation, pelce 005 350 520 540 485 550 575 010 595545 Cured 90 at 307 I1.:

Modulus, psi/300%. 1,150 1,140 1,120 1, 250 1,125 1,115 1,105 1,1051,115 1, 015 Tensile, 2,050 1,770 1,120 1, 000 1, 550 1,575 1,905 1,0550 1,795 Elongation, percent 540 550 3 335 445 450 505 495 450 500Gooilrif h Flexometer, 45'] Dynamic drift, percent 5.0 5.4 0.5 4.4 10.28.7 7.4 7.0 8.0 Final dynamic comp,

percent 10. 0 10. s 10.4 s. 0 13.8 11.0 12. 8 12. 3 11.8 Compressionset, percent 9. 0 s. 5 10.1 7. 9 13. 9 11.8 10.4 11. 1 11.8 Maximumtempera ture rise, 0 20 20 20 20 20 19 21 20 20 21 To max. temperature,

min 1s 20 10 12 20 24 1s 14 20 20 Appearance 0 0 0 0 0 0 6 2 2 0 Shore"A" 52 51 55 53 52 51 50 52 51 50 Mooney scorch (30/ M1 30 25 20 24 23M8 11' 10' 19 17' 15' MS 12' 21' 21' 19' 17' MF- 100/15' 71 73 78 02 1Isooctane. 1 Decalin. 3 Very low.

The compounds were press-cured at 307 F. for 5, 15, 25, 45 and 90minutes. No problems were encountered in these operations and theappearances of the resulting vulcanizates were excellent.

FIGURE III shows the efiect of iodine concentration in the reaction oncure rate of the resultant polymer. In a similar manner, other variablesthat gave an increase in iodine numbers gave improved cure rates, e.g.time, temperature, etc.

This invention is applicable also to alpha olefin homoand copolymerssuch as are produced by Ziegler catalysts, e.g. polyethylene,polypropylene, etc.

The advantages of this invention will be apparent to those skilled inthe art. Modified products of improved curing rates are obtained alongwith high Mooneys, no breakdown as in other halogenations, more oilextendable than other halogenated butyls and better physical and dynamicproperties.

It is to be understood that this invention is not limited to thespecific examples which have been offered merely as illustrations andthat modifications may be made without departing from the spirit of theinvention.

What is claimed is:

1. A process for modifying a rubbery copolymer of 90 to 99.5 wt. percentof an isoolefin having 4 to 8 carbon atoms and 05-10 wt. percent of aconjugated diolefin having 4 to 14 carbon atoms and having a Wijs iodinenumber between about 1 and 50 which comprises treating the copolymerwith elemental iodine and a pyridine-type amine having a formulaselected from the group consisting of:

and

ofi ofi in which y is selected from the group consisting of R, OR, andOH; R being selected from the group consisting of C to C alkyl,cycloalkyl, aryl, aralkyl and alkaryl, n being an integer between 0 and3, at a temperature in the range of about to 150 C. in the presence of apolar organic solvent whereby the iodine number of the copolymer issubstantially increased and separating the modified product which issubstantially free of iodine.

2. The process of claim 1 in which the isoolefin is isobutylene and themultiolefin is isoprene.

3. The process of claim 2 in which the amine is utilized in an amount ofabout 1 to wt. percent based on the copolymer.

4. The process of claim 3 in which the iodine is utilized in an amountof from 1 to 25 wt. percent based on the copolymer.

5. The process of claim 4 in which the time utilized is about A to 2hours.

6. The process of claim 5 in which the modified copolymer has an iodinenumber about double its initial value.

7. The process of claim 5 in which the polar solvent is chlorobenzene.

8. The process of claim 2 in which the pyridine-type amine is pyridine.

References Cited in the file of this patent UNITED STATES PATENTS2,361,072 Vining Oct. 24, 1944 2,596,878 Veersen May 13, 1952 2,631,984Crawford Mar. 17, 1953 2,739,141 Ernst Mar. 20, 1956 2,809,372 FrederickOct. 8, 1957

1. A PROCESS FOR MODIFYING A RUBBERY COPOLYMER OF 90 TO 99.5 WT. PERCENTOF AN ISOOLEFIN HAVING 4 TO 8 CARBON ATOMS AND 0.5-10WT. PERCENT OF ACONJUGATED DIOLEFIN HAVING 4 TO 14 CARBON ATOMS AND HAVING A WIJISIODINE NUMBER; BETWEEN ABOUT 1 AND 50 WHICH COMPRISES TREATING THECOPOLYMER WITH ELEMENTAL IODINE AND A PYRIDINE-TYPE AMINE HAVING AFORMULA SELECTED FROM THE GROUP CONSISTING OF: